1. Field of the Invention
The present invention relates to a communication channel establishing method that involves searching beacons transmitted from a base station, receiving a beacon according to the search result, and establishing a communication channel with the base station based on the received beacon; a communication system using such a method; and a communication apparatus.
2. Description of the Related Art
In an electronic inventory tag system, electronic inventory tags having rewritable display information are registered in a host computer to then be placed on product shelves, and the host computer may access the electronic inventory tags via an access point to rewrite the display information of the electronic inventory tags at the host computer side (e.g. see Japanese Laid-Open Patent Publications No. 2002-304673, No. 2005-99888, No. 2002-109177, No. 2004-265196, and No. 9-138892).
In such an electronic inventory tag system, a communication system is used that determines a communication channel for establishing communication between an electronic inventory tag and an access point using a beacon. In the case where the communication system using a beacon is implemented, an electronic inventory tag scans all available communication channels to determine the communication channel to be established with an access point.
However, according to such a communication method, once communication between a coordinator and a node is shut off, the node has to search all communication channels to reestablish the communication channel with the coordinator. In this case, when the coordinator is unable to establish communication due to power failure, for example, the node may keep on searching all communication channels even though a communication counterpart cannot be accessed and power may needlessly be consumed. Also, even when the coordinator recovers from power failure, a long recovery time may be needed to reestablish the communication channel since the node has to search all communication channels.
It is noted that in the electronic inventory tag system, the electronic tags corresponding to nodes are driven by batteries, and therefore, measures for reducing the power consumption of the electronic inventory tags are in demand.